Buggy code:
public class RSP_services_csparql_API { private String serverAddress ; private URI uri ; private DefaultHttpClient client ; private HttpResponse httpResponse ; private HttpEntity httpEntity ; private HttpParams httpParams ; private ArrayList < BasicNameValuePair > formparams ; private UrlEncodedFormEntity requestParamsEntity ; private PoolingClientConnectionManager cm ; private Logger logger = LoggerFactory . getLogger ( RSP_services_csparql_API . class . getName ( ) ) ; private Gson gson ; public RSP_services_csparql_API ( String serverAddress ) { } public String registerStream ( String inputStreamName ) throws ServerErrorException , StreamErrorException { } public String unregisterStream ( String inputStreamName ) throws ServerErrorException , StreamErrorException { } public String feedStream ( String inputStreamName , String RDF_Data_Serialization ) throws ServerErrorException , StreamErrorException { } public String feedStream ( String inputStreamName , Model model ) throws ServerErrorException , StreamErrorException { } public String getStreamInfo ( String inputStreamName ) throws ServerErrorException , StreamErrorException { } public String getStreamsInfo ( ) throws ServerErrorException , StreamErrorException { } public String registerQuery ( String queryName , String queryBody ) throws QueryErrorException , ServerErrorException { } public String unregisterQuery ( String queryURI ) throws QueryErrorException , ServerErrorException { } public String getQueryInfo ( String queryURI ) throws QueryErrorException , ServerErrorException { } public String getQueriesInfo ( ) throws QueryErrorException , ServerErrorException { } public String pauseQuery ( String queryURI ) throws QueryErrorException , ServerErrorException { } public String restartQuery ( String queryURI ) throws QueryErrorException , ServerErrorException { } public String addObserver ( String queryURI , String callbackUrl ) throws ObserverErrorException , ServerErrorException { } public String deleteObserver ( String observerURI ) throws ObserverErrorException , ServerErrorException { } public String getObserverInformations ( String observerURI ) throws ObserverErrorException , ServerErrorException { } public String getObserversInformations ( String queryURI ) throws ObserverErrorException , ServerErrorException { HttpGet method = null ; String httpEntityContent ; try { uri = new URI ( ( queryURI + "//observers" ) ) ; method = new HttpGet ( uri ) ; method . setHeader ( "Cache-Control" , "no-cache" ) ; httpResponse = client . execute ( method ) ; httpEntity = httpResponse . getEntity ( ) ; logger . debug ( "HTTPResponse<seq2seq4repair_space>code<seq2seq4repair_space>for<seq2seq4repair_space>URI<seq2seq4repair_space>{}:<seq2seq4repair_space>{}" , uri . toString ( ) , httpResponse . getStatusLine ( ) . getStatusCode ( ) ) ; httpParams = client . getParams ( ) ; HttpConnectionParams . setConnectionTimeout ( httpParams , 30000 ) ; InputStream istream = httpEntity . getContent ( ) ; httpEntityContent = streamToString ( istream ) ; if ( ( istream . available ( ) ) != 0 ) EntityUtils . consume ( httpEntity ) ; if ( ( httpResponse . getStatusLine ( ) . getStatusCode ( ) ) == 200 ) { <START_BUG> return gson . fromJson ( httpEntityContent , String . class ) ; <END_BUG> } else { throw new ObserverErrorException ( ( ( ( "Error<seq2seq4repair_space>while<seq2seq4repair_space>getting<seq2seq4repair_space>information<seq2seq4repair_space>about<seq2seq4repair_space>observers<seq2seq4repair_space>attached<seq2seq4repair_space>to<seq2seq4repair_space>query<seq2seq4repair_space>" + queryURI ) + ".<seq2seq4repair_space>ERROR:<seq2seq4repair_space>" ) + httpEntityContent ) ) ; } } catch ( UnsupportedEncodingException e ) { logger . error ( "error<seq2seq4repair_space>while<seq2seq4repair_space>encoding" , e ) ; method . abort ( ) ; } catch ( URISyntaxException e ) { logger . error ( "error<seq2seq4repair_space>while<seq2seq4repair_space>creating<seq2seq4repair_space>URI" , e ) ; } catch ( ClientProtocolException e ) { logger . error ( "error<seq2seq4repair_space>while<seq2seq4repair_space>calling<seq2seq4repair_space>rest<seq2seq4repair_space>service" , e ) ; method . abort ( ) ; } catch ( IOException e ) { method . abort ( ) ; throw new ServerErrorException ( "unreachable<seq2seq4repair_space>host" ) ; } return "Error" ; } public String launchUpdateQuery ( String queryBody ) throws QueryErrorException , ServerErrorException { } public String putStaticModel ( String iri , String location ) throws ServerErrorException , StaticKnowledgeErrorException , URISyntaxException { } public String removeStaticModel ( String iri ) throws ServerErrorException , StaticKnowledgeErrorException , URISyntaxException { } private String streamToString ( InputStream is ) { } }

Fix:
return httpEntityContent ;